A local hidden-variable model for experimental tests of the GHZ puzzle

TL;DR

This paper presents a local hidden-variable model that can replicate experimental results of the GHZ puzzle, challenging the interpretation of such experiments as definitive tests of quantum nonlocality.

Contribution

It introduces a physically motivated local hidden-variable model based on amplitude-threshold detection capable of mimicking GHZ experiment outcomes.

Findings

Detection efficiencies are within local realism bounds.

Model exhibits correlations even with spacelike separated detectors.

Higher detection thresholds improve quantum prediction agreement.

Abstract

The Greenberger-Horne-Zeilinger (GHZ) puzzle has been used to study quantum nonlocality and provide an all-or-nothing, no-go theorem for local hidden-variable models. Recent experiments using coincident-detected entangled photons prepared in a three-particle GHZ state have been used to test quantum nonlocality, but fail to rule out local realism due to a reliance on the fair-sampling hypothesis and insufficient detection efficiency. This paper describes a physically motivated local hidden-variable model based on amplitude-threshold detection that is capable of producing similar results. Detection efficiencies for the model are within the bounds permitted for local realism and, interestingly, exhibit statistical correlations between detectors, even when the detection events are spacelike separated. Increasing the detection threshold improves agreement with the ideal quantum predictions at the cost of decreased detection efficiency. A curious emergent feature of the model is that detection efficiencies may depend upon which observables are chosen for measurement.